The condensation of acetone and/or isopropanol to higher ketones is well known. For example, U.S. Pat. No. 6,977,314 discloses the condensation of acetone to methyl isobutyl ketone (MIBK) with a catalyst consisting of a polysulfonated ion exchange resin containing metal ions. U.S. Pat. No. 6,762,328 and U.S. Pat. No. 6,518,462 disclose a process to make MIBK by reactive distillation. In a first step acetone is condensed to mesityl oxide (MSO). In a second step MSO is hydrogenated to MIBK and small amounts of MIBC (also known as methylamyl alcohol). U.S. Pat. No. 6,706,928 discloses a vapor condensation process to convert acetone to MSO followed by hydrogenation of MSO to MIBK. This patent also discloses a single step condensation/hydrogenation process of acetone to MIBK. U.S. Pat. No. 5,925,796 discloses feeding MIBC and/or MSO with acetone and/or isopropanol to a multifunctional condensation/hydrogenation/dehydration catalyst in order to adjust the MIBK to DIBK (diisobutyl ketone) ratio in the product.
In one known process, MIBK, MIBC, DLBK and IBHK are co-produced in parallel, mixed ketone converters. Isopropanol and hydrogen are fed to the reaction system and through a series of condensation/hydrogenation/dehydration steps, the various products are generated. These condensation/hydrogenation/dehydration reactions can be carried out using a single multifunctional catalyst comprising copper, chromium and calcium carried on an aluminum oxide support. These products can be produced in specified amounts on a continuous basis. The ratio of products can be adjusted to a limited extent by altering the reaction conditions. The reaction chemistry for making these products is shown in FIG. 1.
Additional MIBC is produced by feeding refined MIBK produced in the mixed-ketone converters to a separate single hydrogenation converter containing a nickel-based catalyst.
IBHK is made in parallel by reaction 6 schematically shown in FIG. 1. Optionally, IBHK can be made in isolated campaigns. This is done by feeding MIBK and MIBC at high temperature (240 C) over a single multifunctional catalyst comprising copper, chromium and calcium carried on an aluminum oxide support. IBHK is partially hydrogenated in situ to its corresponding alcohol TMN (the hydrogen is ultimately derived from the dehydrogenation of IPA), thus producing a near equilibrium mixture of IBHK and TMN.
Of continuing interest is a process to increase the IBHK plus TMN capacity while eliminating the need for separate, labor intensive campaigns. Also of interest is a process that has a lower conversion cost and fewer hydrocarbon impurities, and eliminates concerns associated with the conventionally used, more expensive Ni-catalysts.